Wireless power transfer method, apparatus and system for low and medium power

ABSTRACT

A wireless power transfer method for a wireless power transfer apparatus using full and half-bridge inverter topologies includes detecting whether or not a wireless power receiver is present within a range of power being transferrable in a wireless manner, transmitting a detection signal to the wireless power receiver, receiving at least one of identification information and setting information from the wireless power receiver, receiving a control error packet from the wireless power receiver, and controlling an amount of power to be transferred by using the combination of a driving frequency, a duty cycle or a power signal phase to the full or half-bridge inverter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of co-pending U.S. patentapplication Ser. No. 15/018,946 filed Feb. 9, 2016, which is acontinuation of prior U.S. patent application Ser. No. 13/936,897 filedon Jul. 8, 2013 (now U.S. Pat. No. 9,287,039), which claims priority toU.S. Provisional Application Nos. 61/669,504 filed on Jul. 9, 2012, and61/815,126 filed on Apr. 23, 2013, which claims priority under 35 U.S.C.§ 119 to Korean Application No. 10-2013-0077368 filed in Korea on Jul.2, 2013, whose entire disclosures are hereby incorporated by reference.

BACKGROUND 1. Field

This specification relates to a wireless power transfer method,apparatus and system in a wireless power transfer field.

2. Background

In recent years, the method of contactlessly supplying electrical energyto wireless power receivers in a wireless manner has been used insteadof the traditional method of supplying electrical energy in a wiredmanner. The wireless power receiver receiving energy in a wirelessmanner may be directly driven by the received wireless power, or abattery may be charged by using the received wireless power, thenallowing the wireless power receiver to be driven by the charged power.

The Wireless Power Consortium (WPC) which manages technologies for amagnetic inductive wireless power transfer has published a standarddocument “System description Wireless Power Transfer, Volume 1, LowPower, Part 1: Interface Definition, Version 1.00 Release Candidate 1(RC1)” for interoperability in the wireless power transfer on Apr. 22,2010. The standard document of the WPC has described a method oftransferring power from one wireless power transmitter to one wirelesspower receiver by a magnetic induction.

The version 1.00 is involved with low power of 5 W power transmissionand reception. A standard for power transfer over 5 W has not currentlybeen defined in the wireless power transfers regulated in the WPC but aspecification for medium power transmission and reception over 5 W isexpected to be carried out.

SUMMARY OF THE DISCLOSURE

Therefore, an aspect of the detailed description is to provide awireless power transfer method, a wireless power transfer apparatus anda wireless charging system for medium power, capable of beinginteroperable with a low power receiver.

Another aspect of the detailed description is to provide a standard forallowing interoperability between medium power and low power bytransmitting and receiving signals in a form different form from theexisting form, in a wireless power transfer method.

To achieve these and other advantages and in accordance with the purposeof this specification, as embodied and broadly described herein, thereis provided a wireless power transfer method for a wireless powertransfer apparatus using full and half-bridge inverter topologies, themethod including detecting whether or not a wireless power receiver ispresent within a range of power being transferrable in a wirelessmanner, transmitting a detection signal to the wireless power receiver,receiving at least one of identification information and settinginformation from the wireless power receiver, receiving a control errorpacket from the wireless power receiver, and controlling an amount ofpower to be transferred by using the combination of a driving frequency,a duty cycle or a power signal phase to the full or half-bridgeinverter.

In accordance with one exemplary embodiment, the inverter topology maybe changed from the half-bridge into the full-bridge after receiving thefirst control error packet from a medium power wireless power receiver.

The amount of power to be transferred may be selected based on versioninformation in an identification packet collected from the wirelesspower receiver when the first control error packet is received. Thedriving frequency may be shifted in response to the conversion from thehalf-bridge to the full-bridge.

In accordance with another exemplary embodiment, a power transfer unitof the wireless power transmitter may use a voltage corresponding to thehalf-bridge as an initial voltage.

The wireless power transmitter may drive the power transfer unit usingone of the full-bridge inverter and the half-bridge inverter based onwhether the wireless power receiver corresponds either to a medium powerreceiver or to a low power receiver, informed by the wireless powerreceiver.

In accordance with another exemplary embodiment, the wireless powertransmitter may receive the identification packet from the wirelesspower receiver, and the identification packet may contain versioninformation related to the wireless power receiver.

The wireless power transmitter may initially drive an LC circuit usingthe half-bridge inverter, and determine whether or not to change (orconvert) the inverter topology from the half-bridge into the full-bridgebased on the version information. The wireless power transmitter maychange the inverter topology from the half-bridge into the full-bridgewhen the version information corresponds to medium power, and maintainthe half-bridge inverter when the version information corresponds to lowpower.

In accordance with another exemplary embodiment, the driving frequencyused at the step of detecting whether or not the wireless power receiveris present may be 140 kHz.

The detailed description also provides a method of receiving power in awireless manner from a wireless power transmitter using full andhalf-bridge inverter topologies. The method may include transmitting adetection signal to the wireless power transmitter, transmitting atleast one of identification information and setting information to thewireless power transmitter, and transmitting a control error packet tothe wireless power transmitter, wherein the wireless power receivertransmits version information to the wireless power transmitter suchthat the wireless power transmitter controls an amount of power to betransferred by using the combination of a driving frequency, a dutycycle or a power signal phase to the full or half-bridge inverter.

The detailed description also provides a wireless power transmitterusing full and half-bridge inverter topologies, the wireless powertransmitter configured to detect whether or not a wireless powerreceiver is present within a range of power being transferrable in awireless manner, transmit a detection signal to the wireless powerreceiver, receive at least one of identification information and settinginformation from the wireless power receiver, receive a control errorpacket from the wireless power receiver, and control an amount of powerto be transferred by using the combination of a driving frequency, aduty cycle or a power signal phase to the full or half-bridge inverter.

The detailed description also provides a wireless charging systemincluding a wireless power transmitter configured to transmit power in awireless manner, and a wireless power receiver configured to receive thepower from the wireless power transmitter in the wireless manner,wherein a power transfer unit of the wireless power transmitter includesan LC circuit configured to be switched between a full-bridge and ahalf-bridge, wherein the wireless power receiver informs the wirelesspower transmitter of whether or not the wireless power receiver itselfcorresponds to a medium power receiver or a low power receiver such thatthe wireless power transmitter decides whether to drive the powertransfer unit using either the full-bridge or the half-bridge.

The present disclosure proposes an LC resonance driving method forinteroperability between a wireless power transmitter and a wirelesspower receiver having different power capacities, which may extend anemployment range of the wireless power transmitter and receiver. In moredetail, the transmitter may detect whether the receiver is a low powerreceiver or a medium power receiver, and select an LC resonance drivingmode. This may result in interoperability of different power receiversbetween wireless chargers.

Also, the present disclosure proposes a method for securinginteroperability with a low power receiver in Chapter 3.2.2 PowerTransmitter design MP-A2 of “Wireless Power Transfer Volume II: MediumPower Part 1: Interface Definition,” which is undergoing in the WPC. Inmore detail, the present disclosure proposes a method of allowing amedium power (˜15 W) transmission system to be interoperable with 5 Wreception system by changing driving methods (modes) of bridge circuitsafter reception of a first control error (packet).

Further scope of applicability of the present application will becomemore apparent from the detailed description given hereinafter. However,it should be understood that the detailed description and specificexamples, while indicating preferred embodiments of the disclosure, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the disclosure will becomeapparent to those skilled in the art from the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will be described in detail with reference to thefollowing drawings in which like reference numerals refer to likeelements wherein:

FIG. 1 is an exemplary view conceptually illustrating a wireless powertransmitter and a wireless power receiver according to the embodimentsof the present invention;

FIGS. 2A and 2B are exemplary block diagrams illustrating theconfiguration of a wireless power transmitter and a wireless powerreceiver that can be employed in the embodiments disclosed herein,respectively;

FIG. 3 is a view illustrating a concept in which power is transferredfrom a wireless power transmitter to a wireless power receiver in awireless manner according to an inductive coupling method;

FIGS. 4A and 4B are a block diagram illustrating part of the wirelesspower transmitter and wireless power receiver in a magnetic inductionmethod that can be employed in the embodiments disclosed herein;

FIG. 5 is a block diagram illustrating a wireless power transmitterconfigured to have one or more transmitting coils receiving poweraccording to an inductive coupling method that can be employed in theembodiments disclosed herein;

FIG. 6 is a view illustrating a concept in which power is transferred toa wireless power receiver from a wireless power transmitter in awireless manner according to a resonance coupling method;

FIGS. 7A and 7B are a block diagram illustrating part of the wirelesspower transmitter and wireless power receiver in a resonance method thatcan be employed in the embodiments disclosed herein;

FIG. 8 is a block diagram illustrating a wireless power transmitterconfigured to have one or more transmitting coils receiving poweraccording to a resonance coupling method that can be employed in theembodiments disclosed herein;

FIG. 9 a view illustrating a concept of transmitting and receiving apacket between a wireless power transmitter and an electronic devicethrough the modulation and demodulation of a wireless power signal intransferring power in a wireless manner disclosed herein;

FIG. 10 is a view illustrating a configuration of transmitting andreceiving a power control message in transferring power in a wirelessmanner disclosed herein;

FIG. 11 is a view illustrating forms of signals upon modulation anddemodulation executed in a wireless power transfer disclosed herein;

FIG. 12 is a view illustrating a packet including a power controlmessage used in a contactless (wireless) power transfer method accordingto the embodiments disclosed herein;

FIG. 13 is a view illustrating operation phases of the wireless powertransmitter and wireless power receiver according to the embodimentsdisclosed herein;

FIGS. 14, 15A-15B, and 16-18 are views illustrating the structure ofpackets including a power control message between the wireless powertransmitter 100 and the wireless power receiver;

FIG. 19 is a conceptual view illustrating a method of transferring powerto at least one wireless power receiver from a wireless powertransmitter;

FIG. 20 is a conceptual view illustrating a WPC communication flowchart;

FIG. 21 is a view illustrating a communication flowchart in the methodin accordance with the one exemplary embodiment;

FIG. 22 is a configuration view of an identification packet of areceiver;

FIG. 23 is a flowchart illustrating a communication flowchart proposedherein;

FIGS. 24 and 25 are conceptual views illustrating an exemplary use ofmedium power;

FIGS. 26 and 27 are configuration views of circuits using a full-bridgeand a half-bridge, respectively;

FIGS. 28 and 29 are configuration views illustrating variations of thecircuits using the full-bridge and the half-bridge, respectively;

FIG. 30 is a flowchart illustrating a communication flowchart accordingto another exemplary embodiment; and

FIGS. 31 and 32 are conceptual views illustrating an exemplary use ofmedium power in accordance with another exemplary embodiment.

DETAILED DESCRIPTION

The technologies disclosed herein may be applicable to wireless powertransfer (contactless power transfer). However, the technologiesdisclosed herein are not limited to this, and may be also applicable toall kinds of power transmission systems and methods, wireless chargingcircuits and methods to which the technological spirit of the technologycan be applicable, in addition to the methods and apparatuses usingpower transmitted in a wireless manner.

It should be noted that technological terms used herein are merely usedto describe a specific embodiment, but not to limit the presentinvention. Also, unless particularly defined otherwise, technologicalterms used herein should be construed as a meaning that is generallyunderstood by those having ordinary skill in the art to which theinvention pertains, and should not be construed too broadly or toonarrowly. Furthermore, if technological terms used herein are wrongterms unable to correctly express the spirit of the invention, then theyshould be replaced by technological terms that are properly understoodby those skilled in the art. In addition, general terms used in thisinvention should be construed based on the definition of dictionary, orthe context, and should not be construed too broadly or too narrowly.

Incidentally, unless clearly used otherwise, expressions in the singularnumber include a plural meaning. In this application, the terms“comprising” and “including” should not be construed to necessarilyinclude all of the elements or steps disclosed herein, and should beconstrued not to include some of the elements or steps thereof, orshould be construed to further include additional elements or steps.

In addition, a suffix “module” or “unit” used for constituent elementsdisclosed in the following description is merely intended for easydescription of the specification, and the suffix itself does not giveany special meaning or function.

Furthermore, the terms including an ordinal number such as first,second, etc. can be used to describe various elements, but the elementsshould not be limited by those terms. The terms are used merely for thepurpose to distinguish an element from the other element. For example, afirst element may be named to a second element, and similarly, a secondelement may be named to a first element without departing from the scopeof right of the invention.

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings, and thesame or similar elements are designated with the same numeral referencesregardless of the numerals in the drawings and their redundantdescription will be omitted.

In describing the present invention, moreover, the detailed descriptionwill be omitted when a specific description for publicly knowntechnologies to which the invention pertains is judged to obscure thegist of the present invention. Also, it should be noted that theaccompanying drawings are merely illustrated to easily explain thespirit of the invention, and therefore, they should not be construed tolimit the spirit of the invention by the accompanying drawings.

Definition

Many-to-one communication: communicating between one transmitter (Tx)and many receivers (Rx)

Unidirectional communication: transmitting a required message only froma receiver to a transmitter

Here, the transmitter and the receiver indicate the same as atransmitting unit (device) and a receiving unit (device), respectively.Hereinafter, those terms may be used together.

Conceptual View of Wireless Power Transmitter and Wireless PowerReceiver

FIG. 1 is an exemplary view conceptually illustrating a wireless powertransmitter and a wireless power receiver according to the embodimentsof the present invention.

Referring to FIG. 1, the wireless power transmitter 100 may be a powertransfer apparatus configured to transfer power required for thewireless power receiver 200 in a wireless manner.

Furthermore, the wireless power transmitter 100 may be a wirelesscharging apparatus configured to charge a battery of the wireless powerreceiver 200 by transferring power in a wireless manner. A case wherethe wireless power transmitter 100 is a wireless charging apparatus willbe described later with reference to FIG. 9.

Additionally, the wireless power transmitter 100 may be implemented withvarious forms of apparatuses transferring power to the wireless powerreceiver 200 requiring power in a contactless state.

The wireless power receiver 200 is a device that is operable byreceiving power from the wireless power transmitter 100 in a wirelessmanner. Furthermore, the wireless power receiver 200 may charge abattery using the received wireless power.

On the other hand, an electronic device for receiving power in awireless manner as described herein should be construed broadly toinclude a portable phone, a cellular phone, a smart phone, a personaldigital assistant (PDA), a portable multimedia player (PMP), a tablet, amultimedia device, or the like, in addition to an input/output devicesuch as a keyboard, a mouse, an audio-visual auxiliary device, and thelike.

The wireless power receiver 200, as described later, may be a mobilecommunication terminal (for example, a portable phone, a cellular phone,and a tablet and the like) or a multimedia device.

On the other hand, the wireless power transmitter 100 may transfer powerin a wireless manner without mutual contact to the wireless powerreceiver 200 using one or more wireless power transfer methods. In otherwords, the wireless power transmitter 100 may transfer power using atleast one of an inductive coupling method based on magnetic inductionphenomenon by the wireless power signal and a magnetic resonancecoupling method based on electromagnetic resonance phenomenon by awireless power signal at a specific frequency.

Wireless power transfer in the inductive coupling method is a technologytransferring power in a wireless manner using a primary coil and asecondary coil, and refers to the transmission of power by inducing acurrent from a coil to another coil through a changing magnetic field bya magnetic induction phenomenon.

Wireless power transfer in the inductive coupling method refers to atechnology in which the wireless power receiver 200 generates resonanceby a wireless power signal transmitted from the wireless powertransmitter 100 to transfer power from the wireless power transmitter100 to the wireless power receiver 200 by the resonance phenomenon.

Hereinafter, the wireless power transmitter 100 and wireless powerreceiver 200 according to the embodiments disclosed herein will bedescribed in detail. In assigning reference numerals to the constituentelements in each of the following drawings, the same reference numeralswill be used for the same constituent elements even though they areshown in a different drawing.

FIGS. 2A and 2B are exemplary block diagrams illustrating theconfiguration of a wireless power transmitter 100 and a wireless powerreceiver 200 that can be employed in the embodiments disclosed herein.

Wireless Power Transmitter

Referring to FIG. 2A, the wireless power transmitter 100 may include apower transmission unit 110. The power transmission unit 110 may includea power conversion unit 111 and a power transmission control unit 112.

The power conversion unit 111 transfers power supplied from atransmission side power supply unit 190 to the wireless power receiver200 by converting it into a wireless power signal. The wireless powersignal transferred by the power conversion unit 111 is generated in theform of a magnetic field or electromagnetic field having an oscillationcharacteristic. For this purpose, the power conversion unit 111 may beconfigured to include a coil for generating the wireless power signal.

The power conversion unit 111 may include a constituent element forgenerating a different type of wireless power signal according to eachpower transfer method. For example, the power conversion unit 111 mayinclude a primary coil for forming a changing magnetic field to induce acurrent to a secondary coil of the wireless power receiver 200.Furthermore, the power conversion unit 111 may include a coil (orantenna) for forming a magnetic field having a specific resonantfrequency to generate a resonant frequency in the wireless powerreceiver 200 according to the resonance coupling method.

Furthermore, the power conversion unit 111 may transfer power using atleast one of the foregoing inductive coupling method and the resonancecoupling method.

Among the constituent elements included in the power conversion unit111, those for the inductive coupling method will be described laterwith reference to FIGS. 4 and 5, and those for the resonance couplingmethod will be described with reference to FIGS. 7 and 8.

On the other hand, the power conversion unit 111 may further include acircuit for controlling the characteristics of a used frequency, anapplied voltage, an applied current or the like to form the wirelesspower signal.

The power transmission control unit 112 controls each of the constituentelements included in the power transmission unit 110 The powertransmission control unit 112 may be implemented to be integrated intoanother control unit (not shown) for controlling the wireless powertransmitter 100.

On the other hand, a region to which the wireless power signal can beapproached may be divided into two types. First, an active area denotesa region through which a wireless power signal transferring power to thewireless power receiver 200 is passed. Next, a semi-active area denotesan interest region in which the wireless power transmitter 100 candetect the existence of the wireless power receiver 200. Here, the powertransmission control unit 112 may detect whether the wireless powerreceiver 200 is placed in the active area or detection area or removedfrom the area. Specifically, the power transmission control unit 112 maydetect whether or not the wireless power receiver 200 is placed in theactive area or detection area using a wireless power signal formed fromthe power conversion unit 111 or a sensor separately provided therein.For instance, the power transmission control unit 112 may detect thepresence of the wireless power receiver 200 by monitoring whether or notthe characteristic of power for forming the wireless power signal ischanged by the wireless power signal, which is affected by the wirelesspower receiver 200 existing in the detection area. However, the activearea and detection area may vary according to the wireless powertransfer method such as an inductive coupling method, a resonancecoupling method, and the like.

The power transmission control unit 112 may perform the process ofidentifying the wireless power receiver 200 or determine whether tostart wireless power transfer according to a result of detecting theexistence of the wireless power receiver 200.

Furthermore, the power transmission control unit 112 may determine atleast one characteristic of a frequency, a voltage, and a current of thepower conversion unit 111 for forming the wireless power signal. Thedetermination of the characteristic may be carried out by a condition atthe side of the wireless power transmitter 100 or a condition at theside of the wireless power receiver 200.

The power transmission control unit 112 may receive a power controlmessage from the wireless power receiver 200. The power transmissioncontrol unit 112 may determine at least one characteristic of afrequency, a voltage and a current of the power conversion unit 111based on the received power control message, and additionally performother control operations based on the power control message.

For example, the power transmission control unit 112 may determine atleast one characteristic of a frequency, a voltage and a current used toform the wireless power signal according to the power control messageincluding at least one of rectified power amount information, chargingstate information and identification information in the wireless powerreceiver 200.

Furthermore, as another control operation using the power controlmessage, the wireless power transmitter 100 may perform a typicalcontrol operation associated with wireless power transfer based on thepower control message. For example, the wireless power transmitter 100may receive information associated with the wireless power receiver 200to be auditorily or visually outputted through the power controlmessage, or receive information required for authentication betweendevices.

In exemplary embodiments, the power transmission control unit 112 mayreceive the power control message through the wireless power signal. Inother exemplary embodiment, the power transmission control unit 112 mayreceive the power control message through a method for receiving userdata.

In order to receive the foregoing power control message, the wirelesspower transmitter 100 may further include a modulation/demodulation unit113 electrically connected to the power conversion unit 111. Themodulation/demodulation unit 113 may modulate a wireless power signalthat has been modulated by the wireless power receiver 200 and use it toreceive the power control message.

In addition, the power transmission control unit 112 may acquire a powercontrol message by receiving user data including a power control messageby a communication means (not shown) included in the wireless powertransmitter 100.

[For Supporting In-Band Two-Way Communication]

Under a wireless power transfer environment allowing for bi-directionalcommunications according to the exemplary embodiments disclosed herein,the power transmission control unit 112 may transmit data to thewireless power receiver 200. The data transmitted by the powertransmission control unit 112 may be transmitted to request the wirelesspower receiver 200 to send the power control message.

Wireless Power Receiver

Referring to FIG. 2B, the wireless power receiver 200 may include apower supply unit 290. The power supply unit 290 supplies power requiredfor the operation of the wireless power receiver 200. The power supplyunit 290 may include a power receiving unit 291 and a power receptioncontrol unit 292.

The power receiving unit 291 receives power transferred from thewireless power transmitter 100 in a wireless manner.

The power receiving unit 291 may include constituent elements requiredto receive the wireless power signal according to a wireless powertransfer method. Furthermore, the power receiving unit 291 may receivepower according to at least one wireless power transfer method, and inthis case, the power receiving unit 291 may include constituent elementsrequired for each method.

First, the power receiving unit 291 may include a coil for receiving awireless power signal transferred in the form of a magnetic field orelectromagnetic field having a vibration characteristic.

For instance, as a constituent element according to the inductivecoupling method, the power receiving unit 291 may include a secondarycoil to which a current is induced by a changing magnetic field. Inexemplary embodiments, the power receiving unit 291, as a constituentelement according to the resonance coupling method, may include a coiland a resonant circuit in which resonance phenomenon is generated by amagnetic field having a specific resonant frequency.

In another exemplary embodiments, when the power receiving unit 291receives power according to at least one wireless power transfer method,the power receiving unit 291 may be implemented to receive power byusing a coil, or implemented to receive power by using a coil formeddifferently according to each power transfer method.

Among the constituent elements included in the power receiving unit 291,those for the inductive coupling method will be described later withreference to FIGS. 4A and 4B, and those for the resonance couplingmethod with reference to FIGS. 7A and 7B.

On the other hand, the power receiving unit 291 may further include arectifier and a regulator to convert the wireless power signal into adirect current. Furthermore, the power receiving unit 291 may furtherinclude a circuit for protecting an overvoltage or overcurrent frombeing generated by the received power signal.

The power reception control unit 292 may control each constituentelement included in the power supply unit 290.

Specifically, the power reception control unit 292 may transfer a powercontrol message to the wireless power transmitter 100. The power controlmessage may instruct the wireless power transmitter 100 to initiate orterminate a transfer of the wireless power signal. Furthermore, thepower control message may instruct the wireless power transmitter 100 tocontrol a characteristic of the wireless power signal.

In exemplary embodiments, the power reception control unit 292 maytransmit the power control message through at least one of the wirelesspower signal and user data.

In order to transmit the foregoing power control message, the wirelesspower receiver 200 may further include a modulation/demodulation unit293 electrically connected to the power receiving unit 291. Themodulation/demodulation unit 293, similarly to the case of the wirelesspower transmitter 100, may be used to transmit the power control messagethrough the wireless power signal. The power communicationsmodulation/demodulation unit 293 may be used as a means for controllinga current and/or voltage flowing through the power conversion unit 111of the wireless power transmitter 100. Hereinafter, a method forallowing the power communications modulation/demodulation unit 113 or293 at the side of the wireless power transmitter 100 and at the side ofthe wireless power receiver 200, respectively, to be used to transmitand receive a power control message through a wireless power signal willbe described.

A wireless power signal formed by the power conversion unit 111 isreceived by the power receiving unit 291. At this time, the powerreception control unit 292 controls the power communicationsmodulation/demodulation unit 293 at the side of the wireless powerreceiver 200 to modulate the wireless power signal. For instance, thepower reception control unit 292 may perform a modulation process suchthat a power amount received from the wireless power signal is varied bychanging a reactance of the power communications modulation/demodulationunit 293 connected to the power receiving unit 291. The change of apower amount received from the wireless power signal results in thechange of a current and/or voltage of the power conversion unit 111 forforming the wireless power signal. At this time, themodulation/demodulation unit 113 at the side of the wireless powertransmitter 100 may detect a change of the current and/or voltage toperform a demodulation process.

In other words, the power reception control unit 292 may generate apacket including a power control message intended to be transferred tothe wireless power transmitter 100 and modulate the wireless powersignal to allow the packet to be included therein, and the powertransmission control unit 112 may decode the packet based on a result ofperforming the demodulation process of the power communicationsmodulation/demodulation unit 113 to acquire the power control messageincluded in the packet.

In addition, the power reception control unit 292 may transmit a powercontrol message to the wireless power transmitter 100 by transmittinguser data including the power control message by a communication means(not shown) included in the wireless power receiver 200.

[For Supporting In-Band Two-Way Communication]

Under a wireless power transfer environment allowing for bi-directionalcommunications according to the exemplary embodiments disclosed herein,the power reception control unit 292 may receive data to the wirelesspower transmitter 100. The data transmitted by the wireless powertransmitter 100 may be transmitted to request the wireless powerreceiver 200 to send the power control message.

In addition, the power supply unit 290 may further include a charger 298and a battery 299.

The wireless power receiver 200 receiving power for operation from thepower supply unit 290 may be operated by power transferred from thewireless power transmitter 100, or operated by charging the battery 299using the transferred power and then receiving the charged power. Atthis time, the power reception control unit 292 may control the charger298 to perform charging using the transferred power.

Hereinafter, description will be given of a wireless power transmitterand a wireless power receiver applicable to the exemplary embodimentsdisclosed herein. First, a method of allowing the wireless powertransmitter to transfer power to the electronic device according to theinductive coupling method will be described with reference to FIGS. 3through 5.

Inductive Coupling Method

FIG. 3 is a view illustrating a concept in which power is transferredfrom a wireless power transmitter to an electronic device in a wirelessmanner according to an inductive coupling method.

When the power of the wireless power transmitter 100 is transferred inan inductive coupling method, if the strength of a current flowingthrough a primary coil within the power transmission unit 110 ischanged, then a magnetic field passing through the primary coil will bechanged by the current. The changed magnetic field generates an inducedelectromotive force at a secondary coil in the wireless power receiver200.

According to the foregoing method, the power conversion unit 111 of thewireless power transmitter 100 may include a transmitting (Tx) coil 1111a being operated as a primary coil in magnetic induction. Furthermore,the power receiving unit 291 of the wireless power receiver 200 mayinclude a receiving (Rx) coil 2911 a being operated as a secondary coilin magnetic induction.

First, the wireless power transmitter 100 and wireless power receiver200 are disposed in such a manner that the transmitting coil 1111 a atthe side of the wireless power transmitter 100 and the receiving coil atthe side of the wireless power receiver 200 are located adjacent to eachother. Then, if the power transmission control unit 112 controls acurrent of the transmitting coil (Tx coil) 1111 a to be changed, thenthe power receiving unit 291 controls power to be supplied to thewireless power receiver 200 using an electromotive force induced to thereceiving coil (Rx coil) 2911 a.

The efficiency of wireless power transfer by the inductive couplingmethod may be little affected by a frequency characteristic, butaffected by an alignment and distance between the wireless powertransmitter 100 and the wireless power receiver 200 including each coil.

On the other hand, in order to perform wireless power transfer in theinductive coupling method, the wireless power transmitter 100 may beconfigured to include an interface surface (not shown) in the form of aflat surface. One or more electronic devices may be placed at an upperportion of the interface surface, and the transmitting coil 1111 a maybe mounted at a lower portion of the interface surface. In this case, avertical spacing is formed in a small-scale between the transmittingcoil 1111 a mounted at a lower portion of the interface surface and thereceiving coil 2911 a of the wireless power receiver 200 placed at anupper portion of the interface surface, and thus a distance between thecoils becomes sufficiently small to efficiently implement contactlesspower transfer by the inductive coupling method.

Furthermore, an alignment indicator (not shown) indicating a locationwhere the wireless power receiver 200 is to be placed at an upperportion of the interface surface. The alignment indicator indicates alocation of the wireless power receiver 200 where an alignment betweenthe transmitting coil 1111 a mounted at a lower portion of the interfacesurface and the receiving coil 2911 a can be suitably implemented. Thealignment indicator may alternatively be simple marks, or may be formedin the form of a protrusion structure for guiding the location of thewireless power receiver 200. Otherwise, the alignment indicator may beformed in the form of a magnetic body such as a magnet mounted at alower portion of the interface surface, thereby guiding the coils to besuitably arranged by mutual magnetism to a magnetic body having anopposite polarity mounted within the wireless power receiver 200.

On the other hand, the wireless power transmitter 100 may be formed toinclude one or more transmitting coils. The wireless power transmitter100 may selectively use some of coils suitably arranged with thereceiving coil 2911 a of the wireless power receiver 200 among the oneor more transmitting coils to enhance the power transmission efficiency.The wireless power transmitter 100 including the one or moretransmitting coils will be described later with reference to FIG. 5.

Hereinafter, configurations of the wireless power transmitter andelectronic device using an inductive coupling method applicable to theembodiments disclosed herein will be described in detail.

Wireless Power Transmitter and Electronic Device in Inductive CouplingMethod

FIGS. 4A and 4B are a block diagram illustrating part of the wirelesspower transmitter 100 and wireless power receiver 200 in a magneticinduction method that can be employed in the embodiments disclosedherein. A configuration of the power transmission unit 110 included inthe wireless power transmitter 100 will be described with reference toFIG. 4A, and a configuration of the power supply unit 290 included inthe wireless power receiver 200 will be described with reference to FIG.4B.

Referring to FIG. 4A, the power conversion unit 111 of the wirelesspower transmitter 100 may include a transmitting (Tx) coil 1111 a and aninverter 1112.

The transmitting coil 1111 a may form a magnetic field corresponding tothe wireless power signal according to a change of current as describedabove. The transmitting coil 1111 a may alternatively be implementedwith a planar spiral type or cylindrical solenoid type.

The inverter 1112 transforms a DC input obtained from the power supplyunit 190 into an AC waveform. The AC current transformed by the inverter1112 drives a resonant circuit including the transmitting coil 1111 aand a capacitor (not shown) to form a magnetic field in the transmittingcoil 1111 a.

In addition, the power conversion unit 111 may further include apositioning unit 1114.

The positioning unit 1114 may move or rotate the transmitting coil 1111a to enhance the effectiveness of contactless power transfer using theinductive coupling method. As described above, it is because analignment and distance between the wireless power transmitter 100 andthe wireless power receiver 200 including a primary coil and a secondarycoil may affect power transfer using the inductive coupling method. Inparticular, the positioning unit 1114 may be used when the wirelesspower receiver 200 does not exist within an active area of the wirelesspower transmitter 100.

Accordingly, the positioning unit 1114 may include a drive unit (notshown) for moving the transmitting coil 1111 a such that acenter-to-center distance of the transmitting coil 1111 a of thewireless power transmitter 100 and the receiving coil 2911 a of thewireless power receiver 200 is within a predetermined range, or rotatingthe transmitting coil 1111 a such that the centers of the transmittingcoil 1111 a and the receiving coil 2911 a are overlapped with eachother.

For this purpose, the wireless power transmitter 100 may further includea detection unit (not shown) made of a sensor for detecting the locationof the wireless power receiver 200, and the power transmission controlunit 112 may control the positioning unit 1114 based on the locationinformation of the wireless power receiver 200 received from thelocation detection sensor.

Furthermore, to this end, the power transmission control unit 112 mayreceive control information on an alignment or distance to the wirelesspower receiver 200 through the power communicationsmodulation/demodulation unit 113, and control the positioning unit 1114based on the received control information on the alignment or distance.

If the power conversion unit 111 is configured to include a plurality oftransmitting coils, then the positioning unit 1114 may determine whichone of the plurality of transmitting coils is to be used for powertransmission. The configuration of the wireless power transmitter 100including the plurality of transmitting coils will be described laterwith reference to FIG. 5.

On the other hand, the power conversion unit 111 may further include apower sensing unit 1115. The power sensing unit 1115 at the side of thewireless power transmitter 100 monitors a current or voltage flowinginto the transmitting coil 1111 a. The power sensing unit 1115 isprovided to check whether or not the wireless power transmitter 100 isnormally operated, and thus the power sensing unit 1115 may detect avoltage or current of the power supplied from the outside, and checkwhether the detected voltage or current exceeds a threshold value. Thepower sensing unit 1115, although not shown, may include a resistor fordetecting a voltage or current of the power supplied from the outsideand a comparator for comparing a voltage value or current value of thedetected power with a threshold value to output the comparison result.Based on the check result of the power sensing unit 1115, the powertransmission control unit 112 may control a switching unit (not shown)to cut off power applied to the transmitting coil 1111 a.

Referring to FIG. 4B, the power supply unit 290 of the wireless powerreceiver 200 may include a receiving (Rx) coil 2911 a and a rectifier2913.

A current is induced into the receiving coil 2911 a by a change of themagnetic field formed in the transmitting coil 1111 a. Theimplementation type of the receiving coil 2911 a may be a planar spiraltype or cylindrical solenoid type similarly to the transmitting coil1111 a.

Furthermore, series and parallel capacitors may be configured to beconnected to the receiving coil 2911 a to enhance the effectiveness ofwireless power reception or perform resonant detection.

The receiving coil 2911 a may be in the form of a single coil or aplurality of coils.

The rectifier 2913 performs a full-wave rectification to a current toconvert alternating current into direct current. The rectifier 2913, forinstance, may be implemented with a full-bridge rectifier made of fourdiodes or a circuit using active components.

In addition, the rectifier 2913 may further include a regulator forconverting a rectified current into a more flat and stable directcurrent. Furthermore, the output power of the rectifier 2913 is suppliedto each constituent element of the power supply unit 290. Furthermore,the rectifier 2913 may further include a DC-DC converter for convertingoutput DC power into a suitable voltage to adjust it to the powerrequired for each constituent element (for instance, a circuit such as acharger 298).

The power communications modulation/demodulation unit 293 may beconnected to the power receiving unit 291, and may be configured with aresistive element in which resistance varies with respect to directcurrent, and may be configured with a capacitive element in whichreactance varies with respect to alternating current. The powerreception control unit 292 may change the resistance or reactance of thepower communications modulation/demodulation unit 293 to modulate awireless power signal received to the power receiving unit 291.

On the other hand, the power supply unit 290 may further include a powersensing unit 2914. The power sensing unit 2914 at the side of thewireless power receiver 200 monitors a voltage and/or current of thepower rectified by the rectifier 2913, and if the voltage and/or currentof the rectified power exceeds a threshold value as a result ofmonitoring, then the power reception control unit 292 transmits a powercontrol message to the wireless power transmitter 100 to transfersuitable power.

Wireless Power Transmitter Configured to Include One or MoreTransmitting Coils

FIG. 5 is a block diagram illustrating a wireless power transmitterconfigured to have one or more transmission coils receiving poweraccording to an inductive coupling method that can be employed in theembodiments disclosed herein.

Referring to FIG. 5, the power conversion unit 111 of the wireless powertransmitter 100 according to the embodiments disclosed herein mayinclude one or more transmitting coils 1111 a-1 to 1111 a-n. The one ormore transmitting coils 1111 a-1 to 1111 a-n may be an array of partlyoverlapping primary coils. An active area may be determined by some ofthe one or more transmitting coils.

The one or more transmitting coils 1111 a-1 to 1111 a-n may be mountedat a lower portion of the interface surface. Furthermore, the powerconversion unit 111 may further include a multiplexer 1113 forestablishing and releasing the connection of some of the one or moretransmitting coils 1111 a-1 to 1111 a-n.

Upon detecting the location of the wireless power receiver 200 placed atan upper portion of the interface surface, the power transmissioncontrol unit 112 may take the detected location of the wireless powerreceiver 200 into consideration to control the multiplexer 1113, therebyallowing coils that can be placed in an inductive coupling relation tothe receiving coil 2911 a of the wireless power receiver 200 among theone or more transmitting coils 1111 a-1 to 1111 a-n to be connected toone another.

For this purpose, the power transmission control unit 112 may acquirethe location information of the wireless power receiver 200. Forexample, the power transmission control unit 112 may acquire thelocation of the wireless power receiver 200 on the interface surface bythe location detection unit (not shown) provided in the wireless powertransmitter 100. For another example, the power transmission controlunit 112 may alternatively receive a power control message indicating astrength of the wireless power signal from an object on the interfacesurface or a power control message indicating the identificationinformation of the object using the one or more transmitting coils 1111a-1 to 1111 a-n, respectively, and determines whether it is locatedadjacent to which one of the one or more transmitting coils based on thereceived result, thereby acquiring the location information of thewireless power receiver 200.

On the other hand, the active area as part of the interface surface maydenote a portion through which a magnetic field with a high efficiencycan pass when the wireless power transmitter 100 transfers power to thewireless power receiver 200 in a wireless manner. At this time, a singletransmitting coil or one or a combination of more transmitting coilsforming a magnetic field passing through the active area may bedesignated as a primary cell. Accordingly, the power transmissioncontrol unit 112 may determine an active area based on the detectedlocation of the wireless power receiver 200, and establish theconnection of a primary cell corresponding to the active area to controlthe multiplexer 1113, thereby allowing the receiving coil 2911 a of thewireless power receiver 200 and the coils belonging to the primary cellto be placed in an inductive coupling relation.

Furthermore, the power conversion unit 111 may further include animpedance matching unit (not shown) for controlling an impedance to forma resonant circuit with the coils connected thereto.

Hereinafter, a method for allowing a wireless power transmitter totransfer power according to a resonance coupling method will bedisclosed with reference to FIGS. 6 through 8.

Resonance Coupling Method

FIG. 6 is a view illustrating a concept in which power is transferred toan electronic device from a wireless power transmitter in a wirelessmanner according to a resonance coupling method.

First, resonance will be described in brief as follows. Resonance refersto a phenomenon in which amplitude of vibration is remarkably increasedwhen periodically receiving an external force having the same frequencyas the natural frequency of a vibration system. Resonance is aphenomenon occurring at all kinds of vibrations such as mechanicalvibration, electric vibration, and the like. Generally, when exerting avibratory force to a vibration system from the outside, if the naturalfrequency thereof is the same as a frequency of the externally appliedforce, then the vibration becomes strong, thus increasing the width.

With the same principle, when a plurality of vibrating bodies separatedfrom one another within a predetermined distance vibrate at the samefrequency, the plurality of vibrating bodies resonate with one another,and in this case, resulting in a reduced resistance between theplurality of vibrating bodies. In an electrical circuit, a resonantcircuit can be made by using an inductor and a capacitor.

When the wireless power transmitter 100 transfers power according to theinductive coupling method, a magnetic field having a specific vibrationfrequency is formed by alternating current power in the powertransmission unit 110. If a resonance phenomenon occurs in the wirelesspower receiver 200 by the formed magnetic field, then power is generatedby the resonance phenomenon in the wireless power receiver 200.

The resonant frequency may be determined by the following formula inEquation 1.

$\begin{matrix}{f = \frac{1}{2\pi \sqrt{LC}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

Here, the resonant frequency (f) is determined by an inductance (L) anda capacitance (C) in a circuit. In a circuit forming a magnetic fieldusing a coil, the inductance can be determined by a number of turns ofthe coil, and the like, and the capacitance can be determined by a gapbetween the coils, an area, and the like. In addition to the coil, acapacitive resonant circuit may be configured to be connected thereto todetermine the resonant frequency.

Referring to FIG. 6, when power is transmitted in a wireless manneraccording to the resonance coupling method, the power conversion unit111 of the wireless power transmitter 100 may include a transmitting(Tx) coil 1111 b in which a magnetic field is formed and a resonantcircuit 1116 connected to the transmitting coil 1111 b to determine aspecific vibration frequency. The resonant circuit 1116 may beimplemented by using a capacitive circuit (capacitors), and the specificvibration frequency may be determined based on an inductance of thetransmitting coil 1111 b and a capacitance of the resonant circuit 1116.

The configuration of a circuit element of the resonant circuit 1116 maybe implemented in various forms such that the power conversion unit 111forms a magnetic field, and is not limited to a form of being connectedin parallel to the transmitting coil 1111 b as illustrated in FIG. 6.

Furthermore, the power receiving unit 291 of the wireless power receiver200 may include a resonant circuit 2912 and a receiving (Rx) coil 2911 bto generate a resonance phenomenon by a magnetic field formed in thewireless power transmitter 100. In other words, the resonant circuit2912 may be also implemented by using a capacitive circuit, and theresonant circuit 2912 is configured such that a resonant frequencydetermined based on an inductance of the receiving coil 2911 b and acapacitance of the resonant circuit 2912 has the same frequency as aresonant frequency of the formed magnetic field.

The configuration of a circuit element of the resonant circuit 2912 maybe implemented in various forms such that the power receiving unit 291generates resonance by a magnetic field, and is not limited to a form ofbeing connected in series to the receiving coil 2911 b as illustrated inFIG. 6.

The specific vibration frequency in the wireless power transmitter 100may have LTX, CTX, and may be acquired by using the Equation 1. Here,the wireless power receiver 200 generates resonance when a result ofsubstituting the LRX and CRX of the wireless power receiver 200 to theEquation 1 is same as the specific vibration frequency.

According to a contactless power transfer method by resonance coupling,when the wireless power transmitter 100 and wireless power receiver 200resonate at the same frequency, respectively, an electromagnetic wave ispropagated through a short-range magnetic field, and thus there existsno energy transfer between the devices if they have differentfrequencies.

As a result, an efficiency of contactless power transfer by theresonance coupling method is greatly affected by a frequencycharacteristic, whereas the effect of an alignment and distance betweenthe wireless power transmitter 100 and the wireless power receiver 200including each coil is relatively smaller than the inductive couplingmethod.

Hereinafter, the configuration of a wireless power transmitter and anelectronic device in the resonance coupling method applicable to theembodiments disclosed herein will be described in detail.

Wireless Power Transmitter in Resonance Coupling Method

FIGS. 7A and 7B are a block diagram illustrating part of the wirelesspower transmitter 100 and wireless power receiver 200 in a resonancemethod that can be employed in the embodiments disclosed herein.

A configuration of the power transmission unit 110 included in thewireless power transmitter 100 will be described with reference to FIG.7A.

The power conversion unit 111 of the wireless power transmitter 100 mayinclude a transmitting (Tx) coil 1111 b, an inverter 1112, and aresonant circuit 1116. The inverter 1112 may be configured to beconnected to the transmitting coil 1111 b and the resonant circuit 1116.

The transmitting coil 1111 b may be mounted separately from thetransmitting coil 1111 a for transferring power according to theinductive coupling method, but may transfer power in the inductivecoupling method and resonance coupling method using one single coil.

The transmitting coil 1111 b, as described above, forms a magnetic fieldfor transferring power. The transmitting coil 1111 b and the resonantcircuit 1116 generate resonance when alternating current power isapplied thereto, and at this time, a vibration frequency may bedetermined based on an inductance of the transmitting coil 1111 b and acapacitance of the resonant circuit 1116.

For this purpose, the inverter 1112 transforms a DC input obtained fromthe power supply unit 190 into an AC waveform, and the transformed ACcurrent is applied to the transmitting coil 1111 b and the resonantcircuit 1116.

In addition, the power conversion unit 111 may further include afrequency adjustment unit 1117 for changing a resonant frequency of thepower conversion unit 111. The resonant frequency of the powerconversion unit 111 is determined based on an inductance and/orcapacitance within a circuit constituting the power conversion unit 111by Equation 1, and thus the power transmission control unit 112 maydetermine the resonant frequency of the power conversion unit 111 bycontrolling the frequency adjustment unit 1117 to change the inductanceand/or capacitance.

The frequency adjustment unit 1117, for example, may be configured toinclude a motor for adjusting a distance between capacitors included inthe resonant circuit 1116 to change a capacitance, or include a motorfor adjusting a number of turns or diameter of the transmitting coil1111 b to change an inductance, or include active elements fordetermining the capacitance and/or inductance

On the other hand, the power conversion unit 111 may further include apower sensing unit 1115. The operation of the power sensing unit 1115 isthe same as the foregoing description.

Referring to FIG. 7B, a configuration of the power supply unit 290included in the wireless power receiver 200 will be described. The powersupply unit 290, as described above, may include the receiving (Rx) coil2911 b and resonant circuit 2912.

In addition, the power receiving unit 291 of the power supply unit 290may further include a rectifier 2913 for converting an AC currentgenerated by resonance phenomenon into DC. The rectifier 2913 may beconfigured similarly to the foregoing description.

Furthermore, the power receiving unit 291 may further include a powersensing unit 2914 for monitoring a voltage and/or current of therectified power. The power sensing unit 2914 may be configured similarlyto the foregoing description.

Wireless Power Transmitter Configured to Include One or MoreTransmitting Coils

FIG. 8 is a block diagram illustrating a wireless power transmitterconfigured to have one or more transmission coils receiving poweraccording to a resonance coupling method that can be employed in theembodiments disclosed herein.

Referring to FIG. 8, the power conversion unit 111 of the wireless powertransmitter 100 according to the embodiments disclosed herein mayinclude one or more transmitting coils 1111 b-1 to 1111 b-n and resonantcircuits (1116-1 to 1116-n) connected to each transmitting coils.Furthermore, the power conversion unit 111 may further include amultiplexer 1113 for establishing and releasing the connection of someof the one or more transmitting coils 1111 b-1 to 1111 b-n.

The one or more transmitting coils 1111 b-1 to 1111 b-n may beconfigured to have the same vibration frequency, or some of them may beconfigured to have different vibration frequencies. It is determined byan inductance and/or capacitance of the resonant circuits (1116-1 to1116-n) connected to the one or more transmitting coils 1111 b-1 to 1111b-n, respectively.

For this purpose, the frequency adjustment unit 1117 may be configuredto change an inductance and/or capacitance of the resonant circuits(1116-1 to 1116-n) connected to the one or more transmitting coils 1111b-1 to 1111 b-n, respectively.

In-Band Communication

FIG. 9 a view illustrating the concept of transmitting and receiving apacket between a wireless power transmitter and a wireless powerreceiver through the modulation and demodulation of a wireless powersignal in transferring power in a wireless manner disclosed herein.

As illustrated in FIG. 9, the power conversion unit 111 included in thewireless power transmitter 100 may generate a wireless power signal. Thewireless power signal may be generated through the transmitting coil1111 included in the power conversion unit 111.

The wireless power signal 10 a generated by the power conversion unit111 may arrive at the wireless power receiver 200 so as to be receivedthrough the power receiving unit 291 of the wireless power receiver 200.The generated wireless power signal may be received through thereceiving coil 2911 included in the power receiving unit 291.

The power reception control unit 292 may control themodulation/demodulation unit 293 connected to the power receiving unit291 to modulate the wireless power signal while the wireless powerreceiver 200 receives the wireless power signal. When the receivedwireless power signal is modulated, the wireless power signal may form aclosed-loop within a magnetic field or an electromagnetic field. Thismay allow the wireless power transmitter 100 to sense a modulatedwireless power signal 10 b. The modulation/demodulation unit 113 maydemodulate the sensed wireless power signal and decode the packet fromthe demodulated wireless power signal.

The modulation method employed for the communication between thewireless power transmitter 100 and the wireless power receiver 200 maybe an amplitude modulation. As aforementioned, the amplitude modulationis a backscatter modulation may be a backscatter modulation method inwhich the power communications modulation/demodulation unit 293 at theside of the wireless power receiver 200 changes an amplitude of thewireless power signal 10 a formed by the power conversion unit 111 andthe power reception control unit 292 at the side of the wireless powertransmitter 100 detects an amplitude of the modulated wireless powersignal 10 b.

Modulation and Demodulation of Wireless Power Signal

Hereinafter, description will be given of modulation and demodulation ofa packet, which is transmitted or received between the wireless powertransmitter 100 and the wireless power receiver 200 with reference toFIGS. 10 and 11.

FIG. 10 is a view illustrating a configuration of transmitting orreceiving a power control message in transferring power in a wirelessmanner disclosed herein, and FIG. 11 is a view illustrating forms ofsignals upon modulation and demodulation executed in the wireless powertransfer disclosed herein.

Referring to FIG. 10, the wireless power signal received through thepower receiving unit 291 of the wireless power receiver 200, asillustrated in (a) of FIG. 11, may be a non-modulated wireless powersignal 51. The wireless power receiver 200 and the wireless powertransmitter 100 may establish a resonance coupling according to aresonant frequency, which is set by the resonant circuit 2912 within thepower receiving unit 291, and the wireless power signal 51 may bereceived through the receiving coil 2911 b.

The power reception control unit 292 may modulate the wireless powersignal 51 received through the power receiving unit 291 by changing aload impedance within the modulation/demodulation unit 293. Themodulation/demodulation unit 293 may include a passive element 2931 andan active element 2932 for modulating the wireless power signal 51. Themodulation/demodulation unit 293 may modulate the wireless power signal51 to include a packet, which is desired to be transmitted to thewireless power transmitter 100. Here, the packet may be input into theactive element 2932 within the modulation/demodulation unit 293.

Afterwards, the power transmission control unit 112 of the wirelesspower transmitter 100 may demodulate a modulated wireless power signal52 through an envelope detection, and decode the detected signal 53 intodigital data 54. The demodulation may detect a current or voltageflowing into the power conversion unit 111 to be classified into twostates, a HI phase and a LO phase, and acquire a packet to betransmitted by the wireless power receiver 200 based on digital dataclassified according to the states.

Hereinafter, a process of allowing the wireless power transmitter 100 toacquire a power control message to be transmitted by the wireless powerreceiver 200 from the demodulated digital data will be described.

Referring to (b) of FIG. 11, the power transmission control unit 112detects an encoded bit using a clock signal (CLK) from an envelopedetected signal. The detected encoded bit is encoded according to a bitencoding method used in the modulation process at the side of thewireless power receiver 200. The bit encoding method may correspond toany one of non-return to zero (NRZ) and bi-phase encoding.

For instance, the detected bit may be a differential bi-phase (DBP)encoded bit. According to the DBP encoding, the power reception controlunit 292 at the side of the wireless power receiver 200 is allowed tohave two state transitions to encode data bit 1, and to have one statetransition to encode data bit 0. In other words, data bit 1 may beencoded in such a manner that a transition between the HI state and LOstate is generated at a rising edge and falling edge of the clocksignal, and data bit 0 may be encoded in such a manner that a transitionbetween the HI state and LO state is generated at a rising edge of theclock signal.

On the other hand, the power transmission control unit 112 may acquiredata in a byte unit using a byte format constituting a packet from a bitstring detected according to the bit encoding method. For instance, thedetected bit string may be transferred by using an 11-bit asynchronousserial format as illustrated in (c) of FIG. 12. In other words, thedetected bit may include a start bit indicating the beginning of a byteand a stop bit indicating the end of a byte, and also include data bits(b0 to b7) between the start bit and the stop bit. Furthermore, it mayfurther include a parity bit for checking an error of data. The data ina byte unit constitutes a packet including a power control message.

[For Supporting In-Band Two-Way Communication]

As aforementioned, FIG. 9 has illustrated that the wireless powerreceiver 200 transmits a packet using a carrier signal 10 a formed bythe wireless power transmitter 100. However, the wireless powertransmitter 100 may also transmit data to the wireless power receiver200 by a similar method.

That is, the power transmission control unit 112 may control themodulation/demodulation unit 113 to modulate data, which is to betransmitted to the wireless power receiver 200, such that the data canbe included in the carrier signal 10 a. Here, the power receptioncontrol unit 292 of the wireless power receiver 200 may control themodulation/demodulation unit 293 to execute demodulation so as toacquire data from the modulated carrier signal 10 a.

Packet Format

Hereinafter, description will be given of a structure of a packet usedin communication using a wireless power signal according to theexemplary embodiments disclosed herein.

FIG. 12 is a view illustrating a packet including a power controlmessage used in a contactless (wireless) power transfer method accordingto the embodiments disclosed herein.

As illustrated in (a) of FIG. 12, the wireless power transmitter 100 andthe wireless power receiver 200 may transmit and receive data desired totransmit in a form of a command packet (command_packet) 510. The commandpacket 510 may include a header 511 and a message 512.

The header 511 may include a field indicating a type of data included inthe message 512. Size and type of the message may be decided based on avalue of the field which indicates the type of data.

The header 511 may include an address field for identifying atransmitter (originator) of the packet. For example, the address fieldmay indicate an identifier of the wireless power receiver 200 or anidentifier of a group to which the wireless power receiver 200 belongs.When the wireless power receiver 200 transmits the packet 510, thewireless power receiver 200 may generate the packet 510 such that theaddress field can indicate identification information related to thereceiver 200 itself.

The message 512 may include data that the originator of the packet 510desires to transmit. The data included in the message 512 may be areport, a request or a response for the other party.

According to one exemplary embodiment, the command packet 510 may beconfigured as illustrated in (b) of FIG. 12. The header 511 included inthe command packet 510 may be represented with a predetermined size. Forexample, the header 511 may have a 2-byte size.

The header 511 may include a reception address field. For example, thereception address field may have a 6-bit size.

The header 511 may include an operation command field (OCF) or anoperation group field (OGF). The OGF is a value given for each group ofcommands for the wireless power receiver 200, and the OCF is a valuegiven for each command existing in each group in which the wirelesspower receiver 200 is included.

The message 512 may be divided into a length field 5121 of a parameterand a value field 5122 of the parameter. That is, the originator of thepacket 510 may generate the message by a length-value pair (5121 a-5122a, etc.) of at least one parameter, which is required to represent datadesired to transmit.

Referring to (c) of FIG. 12, the wireless power transmitter 100 and thewireless power receiver 200 may transmit and receive the data in a formof a packet which further has a preamble 520 and a checksum 530 added tothe command packet 510.

The preamble 520 may be used to perform synchronization with datareceived by the wireless power transmitter 100 and detect the start bitof the header 520. The preamble 520 may be configured to repeat the samebit. For instance, the preamble 520 may be configured such that data bit1 according to the DBP encoding is repeated eleven to twenty five times.

The checksum 530 may be used to detect an error that can be occurred inthe command packet 510 while transmitting a power control message.

Operation Phases

Hereinafter, description will be given of operation phases of thewireless power transmitter 100 and the wireless power receiver 200.

FIG. 13 illustrates the operation phases of the wireless powertransmitter 100 and the wireless power receiver 200 according to theembodiments disclosed herein. Furthermore, FIGS. 14 to 18 illustrate thestructures of packets including a power control message between thewireless power transmitter 100 and the wireless power receiver 200.

Referring to FIG. 13, the operation phases of the wireless powertransmitter 100 and the wireless power receiver 200 for wireless powertransfer may be divided into a selection phase (state) 610, a ping phase620, an identification and configuration phase 630, and a power transferphase 640.

The wireless power transmitter 100 detects whether or not objects existwithin a range that the wireless power transmitter 100 can transmitpower in a wireless manner in the selection state 610, and the wirelesspower transmitter 100 sends a detection signal to the detected objectand the wireless power receiver 200 sends a response to the detectionsignal in the ping state 620.

Furthermore, the wireless power transmitter 100 identifies the wirelesspower receiver 200 selected through the previous states and acquiresconfiguration information for power transmission in the identificationand configuration state 630. The wireless power transmitter 100transmits power to the wireless power receiver 200 while controllingpower transmitted in response to a control message received from thewireless power receiver 200 in the power transfer state 640.

Hereinafter, each of the operation phases will be described in detail.

1) Selection State

The wireless power transmitter 100 in the selection state 610 performs adetection process to select the wireless power receiver 200 existingwithin a detection area. The detection area, as described above, refersto a region in which an object within the relevant area can effect onthe characteristic of the power of the power conversion unit 111.Compared to the ping state 620, the detection process for selecting thewireless power receiver 200 in the selection state 610 is a process ofdetecting a change of the power amount for forming a wireless powersignal in the power conversion unit at the side of the wireless powertransmitter 100 to check whether any object exists within apredetermined range, instead of the scheme of receiving a response fromthe wireless power receiver 200 using a power control message. Thedetection process in the selection state 610 may be referred to as ananalog ping process in the aspect of detecting an object using awireless power signal without using a packet in a digital format in theping state 620 which will be described later.

The wireless power transmitter 100 in the selection state 610 can detectthat an object comes in or out within the detection area. Furthermore,the wireless power transmitter 100 can distinguish the wireless powerreceiver 200 capable of transferring power in a wireless manner fromother objects (for example, a key, a coin, etc.) among objects locatedwithin the detection area.

As described above, a distance that can transmit power in a wirelessmanner may be different according to the inductive coupling method andresonance coupling method, and thus the detection area for detecting anobject in the selection state 610 may be different from one another.

First, in case where power is transmitted according to the inductivecoupling method, the wireless power transmitter 100 in the selectionstate 610 can monitor an interface surface (not shown) to detect thealignment and removal of objects.

Furthermore, the wireless power transmitter 100 may detect the locationof the wireless power receiver 200 placed on an upper portion of theinterface surface. As described above, the wireless power transmitter100 formed to include one or more transmitting coils may perform theprocess of entering the ping state 620 in the selection state 610, andchecking whether or not a response to the detection signal istransmitted from the object using each coil in the ping state 620 orsubsequently entering the identification state 630 to check whetheridentification information is transmitted from the object. The wirelesspower transmitter 100 may determine a coil to be used for contactlesspower transfer based on the detected location of the wireless powerreceiver 200 acquired through the foregoing process.

Furthermore, when power is transmitted according to the resonancecoupling method, the wireless power transmitter 100 in the selectionstate 610 can detect an object by detecting that any one of a frequency,a current and a voltage of the power conversion unit is changed due toan object located within the detection area.

On the other hand, the wireless power transmitter 100 in the selectionstate 610 may detect an object by at least any one of the detectionmethods using the inductive coupling method and resonance couplingmethod. The wireless power transmitter 100 may perform an objectdetection process according to each power transmission method, andsubsequently select a method of detecting the object from the couplingmethods for contactless power transfer to advance to other states 620,630, 640.

On the other hand, for the wireless power transmitter 100, a wirelesspower signal formed to detect an object in the selection state 610 and awireless power signal formed to perform digital detection,identification, configuration and power transmission in the subsequentstates 620, 630, 640 may have a different characteristic in thefrequency, strength, and the like. It is because the selection state 610of the wireless power transmitter 100 corresponds to an idle state fordetecting an object, thereby allowing the wireless power transmitter 100to reduce consumption power in the idle state or generate a specializedsignal for effectively detecting an object.

2) Ping State

The wireless power transmitter 100 in the ping state 620 performs aprocess of detecting the wireless power receiver 200 existing within thedetection area through a power control message. Compared to thedetection process of the wireless power receiver 200 using acharacteristic of the wireless power signal and the like in theselection state 610, the detection process in the ping state 620 may bereferred to as a digital ping process.

The wireless power transmitter 100 in the ping state 620 forms awireless power signal to detect the wireless power receiver 200,modulates the wireless power signal modulated by the wireless powerreceiver 200, and acquires a power control message in a digital dataformat corresponding to a response to the detection signal from themodulated wireless power signal. The wireless power transmitter 100 mayreceive a power control message corresponding to the response to thedetection signal to recognize the wireless power receiver 200 which is asubject of power transmission.

The detection signal formed to allowing the wireless power transmitter100 in the ping state 620 to perform a digital detection process may bea wireless power signal formed by applying a power signal at a specificoperating point for a predetermined period of time. The operating pointmay denote a frequency, duty cycle, and amplitude of the voltage appliedto the transmitting (Tx) coil. The wireless power transmitter 100 maygenerate the detection signal generated by applying the power signal ata specific operating point for a predetermined period of time, andattempt to receive a power control message from the wireless powerreceiver 200.

On the other hand, the power control message corresponding to a responseto the detection signal may be a message indicating strength of thewireless power signal received by the wireless power receiver 200. Forexample, the wireless power receiver 200 may transmit a signal strengthpacket 5100 including a message indicating the received strength of thewireless power signal as a response to the detection signal asillustrated in FIG. 15. The packet 5100 may include a header 5120 fornotifying a packet indicating the signal strength and a message 5130indicating strength of the power signal received by the wireless powerreceiver 200. The strength of the power signal within the message 5130may be a value indicating a degree of inductive coupling or resonancecoupling for power transmission between the wireless power transmitter100 and the wireless power receiver 200.

The wireless power transmitter 100 may receive a response message to thedetection signal to find the wireless power receiver 200, and thenextend the digital detection process to enter the identification andconfiguration state 630. In other words, the wireless power transmitter100 maintains the power signal at a specific operating point subsequentto finding the wireless power receiver 200 to receive a power controlmessage required in the identification and configuration state 630.

However, if the wireless power transmitter 100 is not able to find thewireless power receiver 200 to which power can be transferred, then theoperation phase of the wireless power transmitter 100 will be returnedto the selection state 610.

3) Identification and Configuration State

The wireless power transmitter 100 in the identification andconfiguration state 630 may receive identification information and/orconfiguration information transmitted by the wireless power receiver200, thereby controlling power transmission to be effectively carriedout.

The wireless power receiver 200 in the identification and configurationstate 630 may transmit a power control message including its ownidentification information. For this purpose, the wireless powerreceiver 200, for instance, may transmit an identification packet 5200including a message indicating the identification information of thewireless power receiver 200 as illustrated in FIG. 15A. The packet 5200may include a header 5220 for notifying a packet indicatingidentification information and a message 5230 including theidentification information of the electronic device. The message 5230may include information (2531 and 5232) indicating a version of thecontract for contactless power transfer, information 5233 foridentifying a manufacturer of the wireless power receiver 200,information 5234 indicating the presence or absence of an extendeddevice identifier, and a basic device identifier 5235. Furthermore, ifit is displayed that an extended device identifier exists in theinformation 5234 indicating the presence or absence of an extendeddevice identifier, then an extended identification packet 5300 includingthe extended device identifier as illustrated in FIG. 15B will betransmitted in a separate manner. The packet 5300 may include a header5320 for notifying a packet indicating an extended device identifier anda message 5330 including the extended device identifier. When theextended device identifier is used as described above, information basedon the manufacturer's identification information 5233, the basic deviceidentifier 5235 and the extended device identifier 5330 will be used toidentify the wireless power receiver 200.

The wireless power receiver 200 may transmit a power control messageincluding information on expected maximum power in the identificationand configuration state 630. To this end, the wireless power receiver200, for instance, may transmit a configuration packet 5400 asillustrated in FIG. 16. The packet may include a header 5420 fornotifying that it is a configuration packet and a message 5430 includinginformation on the expected maximum power. The message 5430 may includepower class 5431, information 5432 on expected maximum power, anindicator 5433 indicating a method of determining a current of a maincell at the side of the wireless power transmitter, and the number 5434of optional configuration packets. The indicator 5433 may indicatewhether or not a current of the main cell at the side of the wirelesspower transmitter is determined as specified in the contract forwireless power transfer.

On the other hand, the wireless power transmitter 100 may generate apower transfer contract which is used for power charging with thewireless power receiver 200 based on the identification informationand/or configuration information. The power transfer contract mayinclude the limits of parameters determining a power transfercharacteristic in the power transfer state 640.

The wireless power transmitter 100 may terminate the identification andconfiguration state 630 and return to the selection state 610 prior toentering the power transfer state 640. For instance, the wireless powertransmitter 100 may terminate the identification and configuration state630 to find another electronic device that can receive power in awireless manner.

4) Power Transfer State

The wireless power transmitter 100 in the power transfer state 640transmits power to the wireless power receiver 200.

The wireless power transmitter 100 may receive a power control messagefrom the wireless power receiver 200 while transferring power, andcontrol a characteristic of the power applied to the transmitting coilin response to the received power control message. For example, thepower control message used to control a characteristic of the powerapplied to the transmitting coil may be included in a control errorpacket 5500 as illustrated in FIG. 17. The packet 5500 may include aheader 5520 for notifying that it is a control error packet and amessage 5530 including a control error value. The wireless powertransmitter 100 may control the power applied to the transmitting coilaccording to the control error value. In other words, a current appliedto the transmitting coil may be controlled so as to be maintained if thecontrol error value is “0,” reduced if the control error value is anegative value, and increased if the control error value is a positivevalue.

The wireless power transmitter 100 may monitor parameters within a powertransfer contract generated based on the identification informationand/or configuration information in the power transfer state 640. As aresult of monitoring the parameters, if power transmission to thewireless power receiver 200 violates the limits included in the powertransfer contract, then the wireless power transmitter 100 may cancelthe power transmission and return to the selection state 610.

The wireless power transmitter 100 may terminate the power transferstate 640 based on a power control message transferred from the wirelesspower receiver 200.

For example, if the charging of a battery has been completed whilecharging the battery using power transferred by the wireless powerreceiver 200, then a power control message for requesting the suspensionof wireless power transfer will be transferred to the wireless powertransmitter 100. In this case, the wireless power transmitter 100 mayreceive a message for requesting the suspension of the powertransmission, and then terminate wireless power transfer, and return tothe selection state 610.

For another example, the wireless power receiver 200 may transfer apower control message for requesting renegotiation or reconfiguration toupdate the previously generated power transfer contract. The wirelesspower receiver 200 may transfer a message for requesting therenegotiation of the power transfer contract when it is required alarger or smaller amount of power than the currently transmitted poweramount. In this case, the wireless power transmitter 100 may receive amessage for requesting the renegotiation of the power transfer contract,and then terminate contactless power transfer, and return to theidentification and configuration state 630.

To this end, a message transmitted by the wireless power receiver 200,for instance, may be an end power transfer packet 5600 as illustrated inFIG. 18. The packet 5600 may include a header 5620 for notifying that itis an end power transfer packet and a message 5630 including an endpower transfer code indicating the cause of the suspension. The endpower transfer code may indicate any one of charge complete, internalfault, over temperature, over voltage, over current, battery failure,reconfigure, no response, and unknown error.

Communication Method of Plural Electronic Devices

Hereinafter, description will be given of a method by which at least oneelectronic device performs communication with one wireless powertransmitter using wireless power signals.

FIG. 19 is a conceptual view illustrating a method of transferring powerto at least one wireless power receiver from a wireless powertransmitter.

The wireless power transmitter 100 may transmit power to one or morewireless power receivers 200 and 200′. FIG. 19 illustrates twoelectronic devices 200 and 200′, but the methods according to theexemplary embodiments disclosed herein may not be limited to the numberof electronic devices shown.

An active area and a detection area may be different according to thewireless power transfer method of the wireless power transmitter 100.Therefore, the wireless power transmitter 100 may determine whetherthere is a wireless power receiver located on the active area or thedetection area according to the resonance coupling method or a wirelesspower receiver located on the active area or the detection areaaccording to the induction coupling method. According to thedetermination result, the wireless power transmitter 100 which supportseach wireless power transfer method may change the power transfer methodfor each wireless power receiver.

In the wireless power transfer according to the exemplary embodimentsdisclosed herein, when the wireless power transmitter 100 transferspower to the one or more electronic devices 200 and 200′ according tothe same wireless power transfer method, the electronic devices 200 and200′ may perform communications through the wireless power signalswithout inter-collision.

Referring to FIG. 19, a wireless power signal 10 a generated by thewireless power transmitter 100 may arrive at the first electronic device200′ and the second electronic device 200, respectively. The first andsecond electronic devices 200′ and 200 may transmit wireless powermessages using the generated wireless power signal 10 a.

The first electronic device 200′ and the second electronic device 200may operate as wireless power receivers for receiving a wireless powersignal. The wireless power receiver in accordance with the exemplaryembodiments disclosed herein may include a power receiving unit 291′,291 to receive the generated wireless power signal, amodulation/demodulation unit 293′, 293 to modulate or demodulate thereceived wireless power signal, and a controller 292′, 292 to controleach component of the wireless power receiver.

The present disclosure proposes a communication protocol selectionmethod in a wireless charging system (or a wireless powertransmitter/receiver) using multiple communication protocols, astructure of a transmitter allowing for interoperability of an inductionmethod and a resonance method in the wireless charging system, and acommunication method of the transmitter allowing for theinteroperability of the induction method and the resonance method.Hereinafter, detailed description thereof will be given.

Also, the present disclosure proposes a method for securinginteroperability with a low power receiver in Chapter 3.2.2 PowerTransmitter design MP-A2 of “Wireless Power Transfer Volume II: MediumPower Part 1: Interface Definition,” which is undergoing in the WPC. Inmore detail, the present disclosure proposes a method of allowing amedium power (˜15 W) transmission system to be interoperable with 5 Wreception system by changing driving methods (modes) of bridge circuitsafter reception of a first control error (packet). Hereinafter, detaileddescription thereof will be given.

Method of Changing Mode of Wireless Power Transmitter According to PowerInformation of Wireless Power Receiver

Hereinafter, a technology of extending a medium power (˜15 W) system toa low power (5 W) system for use by adding a new phase between theidentification & configuration phase and the power transfer phase inChapter 5 System Control in Wireless Power Specification Part 1 SystemDescription of WPC will be described with reference to FIGS. 20 to 32.

First of all, description will be given of a communication protocolselection method in a wireless power transmitter/receiver using mediumpower with reference to FIGS. 20 to 23.

FIG. 20 is a conceptual view illustrating WPC communication flows, FIG.21 is a view illustrating communication flows in a method in accordancewith one exemplary embodiment, FIG. 22 is a configuration view of anidentification packet of a receiver, and FIG. 23 is a flowchartillustrating communication flows proposed herein.

Hardware of a medium power wireless power transmitter may have afull-bridge configuration to transmit higher power than the existingtransmitter. Here, when transferring power to the existing 5 W receiverin the full-bridge mode (or using the full-bridge configuration or thefull-bridge inverter), voltage and current may be greatly abandoned.This may cause a breakdown of the receiver.

Therefore, a method for allowing a medium power wireless powertransmitter to stably transfer power even to the 5 W receiver isrequired.

It is natural that a medium power transmitter TX stably transfers powerto a medium power receiver RX. Interoperability between the medium powertransmitter TX and the existing low power reception system mayadditionally be required. To this end, the present disclosure may allowa TX to carry out an LC driving mode (half-bridge and full-bridge)conversion to be stable and appropriate for each of a low powerreception system and a medium power reception system, based on versioninformation collected from an RX.

As illustrated, at the moment of receiving a first control error afterrecognition of a receiver, a process of determining version informationrelated to an identification packet collected from the RX to change anLC driving mode may be added to the existing WPC communication flows.

As a more detailed example, a wireless power transmitter according tothe present disclosure may use full-bridge and half-bridge invertertopologies. That is, the wireless power transmitter may include a powertransfer unit for switching the full-bridge and half-bridge inverters(or switching the full-bridge and half-bridge modes).

A wireless power transfer method according to the present disclosure mayinclude detecting whether or not a wireless power receiver is presentwithin a range that power can be transferred in a wireless manner, andtransmitting a detection signal to the wireless power receiver. Theseprocesses can be understood by the foregoing description, so detaileddescription thereof will be omitted.

Next, the method may further include receiving at least one ofidentification information and setting information transmitted by thewireless power receiver (S120), and receiving a control error packetfrom the wireless power receiver (S130). As a pre-step of suchinformation collection, half-bridge mode driving may be carried out(S110). Here, the method may further include changing an LC driving modeby determining version information in an identification packet collectedfrom the wireless power receiver, at the time point of receiving thefirst control error after recognition of the receiver in the existingWPC communication flows. Here, the present disclosure may not be limitedto this. For example, a low power receiver or a medium power receivermay also be determined by collecting maximum power information otherthan the version information.

Eventually, in the wireless power transfer method, the wireless powertransmitter may use the combination of an operating frequency, a dutycycle or a phase of the power signal to either the full or half-bridgeinverter in order to control the amount of power to be transferred. Thatis, the wireless power transmitter may drive the power transfer unit inone of the full-bridge driving mode and the half-bridge driving modebased on whether the wireless power receiver is a medium power receiveror a low power receiver, informed by the corresponding wireless powerreceiver (S140).

For example, in the negotiation phase having medium power, afterreceiving the first control error from the medium power receiver, aninverter topology may be changed from the half-bridge (inverter) intothe full-bridge (inverter).

In this case, a problem may be caused in stability of the receiveraccording to whether to switch an initial LC driving mode from thehalf-bridge mode into the full-bridge mode or from the full-bridge modeinto the half-bridge mode. This is why a rectifier voltage of thereceiver is likely to suddenly change by two times or half (½) times dueto the conversion of the LC driving mode used upon recognition of thepower receiver and frequency shifting.

To solve the problem, the inverter topology may be changed from the halfbridge into the full bridge after receiving a first control error packetfrom a medium power wireless power receiver. The amount of power to betransferred may be selected based on the version information in theidentification packet collected from the wireless power receiver whenreceiving the first control error packet. In more detail, in thisexemplary embodiment, the wireless power transmitter may initially driveits LC circuit in the half bridge mode at a frequency with a high gain,and check that the receiver is a medium power receiver. The wirelesspower transmitter may then shift the frequency to a frequency with a lowgain upon conversion into the full bridge after receiving the firstcontrol error packet, thereby preventing a voltage from beingexcessively applied to a secondary side (the receiver side).

As one example, the transmitter may initially drive the LC circuit inthe half-bridge mode at a frequency at high power is transferred to thereceiver. When the receiver is recognized, the transmitter may collectversion information related to the receiver. Here, the receiver maytransmit its own version information to the transmitter through anidentification packet (see FIG. 22). The transmitter may then receivethe version information of the receiver in the identification phase.

The power transfer unit of the wireless power transmitter may use avoltage corresponding to the half-bridge as an initial voltage.Therefore, the initial voltage of the half-bridge may be 12V. Also, aninitial frequency may be set in the range of 135 to 145 kHz (duty cycleof 50%). In more detail, in order to pass a test of the existing lowpower receiver, the frequency may be set to 140 kHz upon recognition ofthe receiver (execution of a digital ping).

Next, when the version information of the receiver is over 2.0, the LCdriving mode may be switched from the half-bridge into the full-bridge,and if not, maintained in the half-bridge driving mode. That is, whenthe version information of the receiver is checked to be over 2.0, thetransmitter may switch its LC circuit to the full-bridge mode totransfer power. When the half-bridge is switched to the full-bridge, anoperating frequency (or driving frequency, hereinafter “drivingfrequency”) may be shifted (S150).

As such, the wireless power transmitter may start driving the LC circuitin the half-bridge mode, and decide whether or not to switch the LCcircuit to the full-bridge based on the version information.

Upon the conversion from the half-bridge to the full-bridge, the TX mayset a start frequency within a range that does not damage a rectifiercircuit of the RX. As one example, when only the driving mode isswitched with maintaining the same frequency, a gain value may increaseby two times. Hence, when the RX requires the gain value less than twotimes, the start frequency of the TX may be set to be over 140 kHz. Thatis, the driving frequency in the full-bridge mode may be over 140 kHz.

FIGS. 24 and 25 are conceptual views illustrating an exemplary use ofmedium power, and FIGS. 26 and 27 are configuration views of circuitsusing a full-bridge and a half-bridge, respectively.

Control of the power transfer shall proceed using the PID algorithm. Asillustrated in FIG. 24, it may be understood that output powercorresponds to the full-bridge when the duty cycle is 40% and the phaseshift is 80%, respectively. Therefore, as illustrated in FIG. 25, thehalf-bridge mode in which a voltage is applied only to Drive 1 may beshifted to the full-bridge mode by shifting phase with applying thevoltage to each of Drive 1 and Drive 2.

As more detailed numerical values, a driving frequency range may befop=110˜205 kHz, and a phase shift range of the full-bridge may be 80 to100%. Also, the driving frequency range may be 50 to 100% at fop=205kHz.

A duty cycle rage of the half-bridge may be 40 to 50% when fop=110˜205kHz, and be 25 to 50% at fop=205 kHz.

A higher driving frequency or a lower phase or duty cycle may result inthe transfer of a lower amount of power. In order to transfer thesufficient amount of power, the driving frequency may be controlled withthe following resolution.

0.07×fop-0.5 kHz for f_(op) in the 110 to 140 kHz range;

0.006×fop-0.4 kHz for f_(op) in the 140 to 205 kHz range.

For hardware configuration, referring to FIG. 26, in the full-bridgemode, a PWM2 pulse of a micom output terminal may be generated in theform of a reversal signal of PWM1 or a phase-shifted form to drive theLC circuit. In the half-bridge mode, referring to FIG. 27, the PWM2pulse of the micom output terminal may be shifted to a ground signal todrive the LC circuit, and accordingly, a half-bridge output may berepresented as shown in the first drawing of FIG. 25. Such hardwareconfiguration may be varied into various forms.

FIGS. 28 and 29 are configuration views illustrating variations of thecircuits using the full-bridge and the half-bridge, respectively.

Unlike the foregoing exemplary embodiment using a synchronous gatedriver, in this exemplary embodiment, drivers may be connected toswitches, respectively, and an LC circuit in the full-bridge mode may bedriven by generating PWM3 and 4 pulses of a micom output terminal intothe form of reversal signals of PWM1 and 2 or the phase-shifted form.Also, the LC circuit in the half-bridge mode may be driven byimplementing the PWM3 pulse of the micom output terminal in the form ofa reversal signal of the PWM1, the PWM2 pulse into a GND, and PWM4 intoa high signal.

Also, the present disclosure may disclose another exemplary embodimentfor the conversion of the initial driving. Hereinafter, the anotherexemplary embodiment will be described in more detail with reference toFIGS. 30 to 32.

FIG. 30 is a flowchart illustrating communication flows according toanother exemplary embodiment, and FIGS. 31 and 32 are conceptual viewsillustrating an exemplary use of medium power in accordance with anotherexemplary embodiment.

As illustrated in FIGS. 30 to 32, the transmitter may initially driveits LC circuit in a full-bridge mode at a frequency with a low gainuntil reception of the first control error according to the existing WPCcommunication flows, and check that the receiver is a low power receiverby receiving and collecting version information (S220), and receive thefirst control error (S230). Afterwards, the transmitter may shift thefrequency to a frequency with a low gain upon conversion into thehalf-bridge mode, thereby preventing a voltage from being excessivelyapplied to a secondary side (the low power receiver).

In more detail, when a low frequency over 205 kHz is required uponrecognition of the receiver (executing a digital ping) in order to passa test for the existing low power interoperable receiver, a phase shiftfor a full-bridge driving signal may be executed or a duty ratio may beadjusted. For example, an initial driving frequency of the full-bridgemay be 205 kHz, and duty cycle may be 40%.

Here, when version information of the receiver is below 2.0, the LCdriving mode may be switched from the full-bridge into the half-bridge(S240), and if not, the full-bridge mode may be maintained. Upon theswitching from the full-bridge into the half-bridge, a problem of adecrease in the amount of power transferred to the receiver may becaused. To compensate for this, the driving frequency may be shifted(S250). As one example, for Tx coil MP-A2, the LC circuit may be drivenat an operating frequency of 140 kHz and a duty cycle of 40%. Then, whenthe version is below 2.0, the frequency of the half-bridge may beshifted to 140 kHz.

Accordingly, Power Transmitter design MP-A2 uses half and full-bridgeinverter topologies to drive the Primary Coil and a series capacitance.Within the operating frequency range specified above, the assembly ofprimary coil and shielding, has a self inductance Lp=7.8 μH. The valueof the series capacitance is Cp=328 nF. The input voltage to theinverter is 12 V. Near resonance, the voltage developed across theseries capacitance can reach levels exceeding 200 V pk-pk.

As such, the receiver may transmit its own version information to thetransmitter through an identification packet, and the transmitter maymaintain the existing LC driving mode until receiving the first controlerror. The transmitter may then determine whether or not the receiver isa low power receiver or a medium power receiver based on the versioninformation of the receiver. According to the determination result, thetransmitter may change the LC driving mode and shift the frequency. Thismay result in removal of risk that a high voltage is applied to thereceiver.

It can be understood by a skilled person in the art that theconfiguration of the wireless power transmitter according to theforegoing embodiments disclosed herein can also be applied to otherdevices, such as a docking station, a cradle device and other electronicdevices, excluding a case of being applicable only to a wirelesscharger.

The foregoing embodiments and advantages are merely exemplary and arenot to be construed as limiting the present disclosure. The presentteachings can be readily applied to other types of apparatuses. Thisdescription is intended to be illustrative, and not to limit the scopeof the claims. Many alternatives, modifications, and variations will beapparent to those skilled in the art. The features, structures, methods,and other characteristics of the exemplary embodiments described hereinmay be combined in various ways to obtain additional and/or alternativeexemplary embodiments.

As the present features may be embodied in several forms withoutdeparting from the characteristics thereof, it should also be understoodthat the above-described embodiments are not limited by any of thedetails of the foregoing description, unless otherwise specified, butrather should be construed broadly within its scope as defined in theappended claims, and therefore all changes and modifications that fallwithin the metes and bounds of the claims, or equivalents of such metesand bounds are therefore intended to be embraced by the appended claims.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the invention. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A wireless power transmitter for transferringwireless power to a wireless power receiver, the wireless powertransmitter comprising: a primary coil configured to perform wirelesspower transfer to a wireless power receiver by using magnetic couplingwith a secondary coil in the wireless power receiver; an inverterconfigured to convert DC input into an AC waveform to drive the primarycoil based on at least one of a half-bridge inverter topology and afull-bridge inverter topology; and a power transmission control unitconfigured to control at least one of an operating frequency or a dutycycle of the inverter, wherein the inverter uses the half-bridgeinverter topology to transmit a ping signal to the wireless powerreceiver, and switches from the half-bridge inverter topology to thefull-bridge inverter topology under a condition that a negotiatedmaximum power of the wireless power receiver is greater than 5 W afterthe wireless power transmitter receives a first control error packetfrom the wireless power receiver.
 2. The wireless power transmitter ofclaim 1, wherein the duty cycle is reduced in response to the switchingfrom the half-bridge inverter topology to the full-bridge invertertopology.
 3. The wireless power transmitter of claim 1, wherein a powertransmission control unit uses a voltage corresponding to thehalf-bridge inverter topology as an initial voltage.
 4. The wirelesspower transmitter of claim 1, wherein the power transmission controlunit receives an identification packet from the wireless power receiver,and the identification packet includes version information related tothe wireless power receiver.
 5. The wireless power transmitter of claim1, wherein the power transmission control unit is further configured toinitially drive an LC circuit using the half-bridge inverter topology,and determines whether or not to change the topology of the inverterfrom the half-bridge inverter topology into the full-bridge invertertopology after receiving the first control error packet.
 6. The wirelesspower transmitter of claim 1, wherein the operating frequency isinitially in the range of 135 kHz to 145 kHz.
 7. A wireless powerreceiver for receiving wireless power from a wireless power transmitter,the wireless power receiver comprising: a secondary coil configured toreceive wireless power from the wireless power transmitter by usingmagnetic coupling with a primary coil in the wireless power transmitterbased on at least one of a half-bridge inverter topology and afull-bridge inverter topology; a rectifier configured to rectify thewireless power into a DC output; and a power reception control unitconfigured to receive a ping signal from the wireless power transmitterbased on the half-bridge inverter topology, wherein the secondary coilreceives the wireless power from the wireless power transmitter based onthe full-bridge inverter topology under a condition that a negotiatedmaximum power of the wireless power receiver is greater than 5 W afterthe wireless power receiver transmits the first control error packet tothe wireless power transmitter.
 8. The wireless power receiver of claim7, wherein the duty cycle of the wireless power is reduced in responseto the switching to the full-bridge inverter topology.
 9. The wirelesspower receiver of claim 7, wherein the operating frequency of thewireless power is initially in the range of 135 kHz to 145 kHz.
 10. Thewireless power receiver of claim 7, wherein the secondary coil receivedthe wireless power from the primary coil, which uses a voltagecorresponding to the half-bridge inverter topology as an initialvoltage.
 11. The wireless power receiver of claim 7, wherein the powerreception control unit transmits an identification packet to wirelesspower transmitter, and the identification packet includes versioninformation related to the wireless power receiver.
 12. A method oftransferring wireless power to a wireless power receiver performed by awireless power transmitter, the method comprising: converting a DC inputinto an AC waveform to drive a primary coil of the wireless powertransmitter based on at least one of a half-bridge inverter topology anda full-bridge inverter topology; transmitting a ping signal to thewireless power receiver by using the half-bridge inverter topology;transferring the wireless power to the wireless power receiver by usingmagnetic coupling between the primary coil and a secondary coil in thewireless power receiver; and switching from the half-bridge invertertopology to the full-bridge inverter topology under a condition that anegotiated maximum power of the wireless power receiver is greater than5 W after the wireless power transmitter receives a first control errorpacket from the wireless power receiver.
 13. The method of claim 12,wherein the wireless power is transferred by controlling at least one ofan operating frequency or a duty cycle of the inverter.
 14. The methodof claim 13, wherein the duty cycle is reduced in response to theswitching from the half-bridge inverter topology to the full-bridgeinverter topology.
 15. The method of claim 12 further comprises:receiving, from the wireless power receiver, a configuration packetincluding a maximum power of the wireless power receiver.